Field
The present invention relates to a method for manufacturing an anode suitable for a cable-type secondary battery and a cable-type secondary battery comprising the same.
Description of Related Art
Secondary batteries are devices capable of storing energy in chemical form and of converting into electrical energy to generate electricity when needed. The secondary batteries are also referred to as rechargeable batteries because they can be recharged repeatedly. Common secondary batteries include lead accumulators, NiCd batteries, NiMH accumulators, Li-ion batteries, Li-ion polymer batteries, and the like. When compared with disposable primary batteries, not only are the secondary batteries more economically efficient, they are also more environmentally friendly.
Secondary batteries are currently used in applications requiring low electric power, for example, equipment to start vehicles, mobile devices, tools, uninterruptible power supplies, and the like. Recently, as the development of wireless communication technologies has been leading to the popularization of mobile devices and even to the mobilization of many kinds of conventional devices, the demand for secondary batteries has been dramatically increasing. Secondary batteries are also used in environmentally friendly next-generation vehicles such as hybrid vehicles and electric vehicles to reduce the costs and weight and to increase the service life of the vehicles.
Generally, secondary batteries have a cylindrical, prismatic, or pouch shape. This is associated with a fabrication process of the secondary batteries in which an electrode assembly composed of an anode, a cathode, and a separator is mounted in a cylindrical or prismatic metal casing or a pouch-shaped casing of an aluminum laminate sheet, and in which the casing is filled with electrolyte. Because a predetermined mounting space for the electrode assembly is necessary in this process, the cylindrical, prismatic or pouch shape of the secondary batteries is a limitation in developing various shapes of mobile devices. Accordingly, there is a need for secondary batteries of a new structure that are adaptable in shape. To fulfill this need, suggestions have been made to develop flexible linear secondary batteries having a very high ratio of length to cross-sectional diameter, hereinafter referred to as cable-type secondary batteries.
However, the flexible cable-type secondary batteries are frequently subject to the external physical impact due to their structural characteristics, which may result in a short circuit. Further, when Si or Sn is used as an anode active material, the active material may fall off due to expansion and shrinkage of electrodes caused by the repeated charging and discharging. For this reason, the performance of the cable-type secondary batteries may deteriorate more severely than general secondary batteries.
Accordingly, it is an object of the present invention to provide an anode of a lithium secondary battery having a pore structure that is excellent in electrochemical reactivity and capable of relieving the stress and pressure in the battery, and a method for manufacturing the same.